PCNSE Practice Question: Securing Users and Applications with Authentication
A network administrator needs to authenticate users accessing the internet through the firewall using Active Directory credentials. Which authentication method should be used to transparently authenticate users without requiring a browser-based captive portal?
⚠ Common exam trap
A common mix-up: candidates confuse NTLM with Kerberos, assuming NTLM can also provide transparent SSO, but NTLM typically requires a browser-based challenge or fails in modern environments due to its lack of mutual authentication and reliance on weaker cryptographic methods.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Kerberos
Kerberos is the correct choice because it enables transparent, single sign-on (SSO) authentication in a Windows Active Directory domain. When a user logs into their domain-joined workstation, Kerberos obtains a Ticket-Granting Ticket (TGT) from the Key Distribution Center (KDC). The firewall can then use Kerberos authentication to verify the user's identity without requiring any browser-based captive portal, as the TGT or service ticket is presented automatically by the client.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
LDAP
Why it's wrong here
LDAP is used for user mapping, not direct authentication.
- ✗
NTLM
Why it's wrong here
NTLM is less secure and often requires a proxy setup.
- ✗
SAML
Why it's wrong here
SAML typically requires a browser redirect and user interaction.
- ✓
Kerberos
Why this is correct
Kerberos provides transparent authentication for domain users.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This PCNSE practice question is part of Courseiva's free Palo Alto Networks certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the PCNSE exam.